@misc{cryptoeprint:2011:065,
author = {Carolin Lunemann and Jesper Buus Nielsen},
title = {Fully Simulatable Quantum-Secure Coin-Flipping and Applications},
howpublished = {Cryptology ePrint Archive, Report 2011/065},
year = {2011},
note = {\url{http://eprint.iacr.org/}},
}
You will need the url.sty package (comes with most LaTeX installations) for the last line. Otherwise, remove the \url command.